A large explosion outside the international airport in Somalia's capital has killed at least eight people and wounded nine others, a local doctor said.

Dr Abdulkadir Adam of Medina Hospital shared the toll with the Associated Press.

Witnesses said a passing US convoy appeared to be the target of the blast near a checkpoint leading to the heavily fortified airport in Mogadishu.

The founder of the Aamin ambulance service, Abdulkadir Adan, tweeted that he was "deeply saddened by the loss of life and injuries".

He posted a photo from the scene of a mangled vehicle.

The al Qaida-linked al-Shabab extremist group that controls parts of Somalia often carries out bombings at high-profile locations in the capital.